In related art, a grommet is in a watertight manner fitted to a through hole formed in a vehicle body panel of a vehicle such as an automobile, and a wire harness is inserted into the grommet in the watertight and irremovable manner.
The grommet includes an inner side harness insertion portion into which the wire harness is inserted, a substantially truncated cone shaped (so-called bowl-like) inner side tubular portion integrated with the inner side harness insertion portion at a small diameter side end, and a panel abutment portion integrally formed at a large diameter side end of the inner side tubular portion. The panel abutment portion cannot enter the through hole, and a vehicle body lock recess is formed at a boundary between the inner side tubular portion and the panel abutment portion. Therefore, the inner side tubular portion is pulled toward an inner side (a direction of the small diameter side end), so that an outer circumference of the inner side tubular portion is reduced in diameter while sliding into the through hole, and the vehicle body lock recess is fitted into the through hole. When a force in a direction away from the inner side is applied by pulling an outer side portion toward an outer side after mounting, the vehicle body lock recess may be removed from the through hole since the vehicle body lock recess is stretched and an outer diameter is reduced (for example, see Patent Literature 1).
Therefore, a grommet is disclosed in which the panel abutment portion is difficult to be removed from the through hole even if the panel abutment portion is pulled toward the outer side. More specifically, in the grommet, an annular inner side lip that can enter the through hole and an annular outer side lip that cannot enter the through hole are integrally formed, a fitting portion is formed at a boundary between an outer circumferential edge of the inner side lip and an outer circumferential edge of the outer side lip, and an outer circumference of a cylinder into which the wire harness is inserted and an inner circumference of the inner side lip are connected by a connection portion. At this time, since a position where the connection portion is connected at the inner side lip is between a position where the connection portion is connected at the cylinder and a position of the fitting portion, the connection portion is axially contracted and an outer diameter of the fitting portion is increased when a force is applied to push the cylinder in a fitting portion direction, so that a remarkable effect is obtained that mounting is ensured and stability is enhanced (for example, see Patent Literature 2).